Fix path to pexpect's bashrc, to make tests more reliable.  The path
was changed in 46e6e75
to `replwrap/bashrc.sh` inside pexpect package; however, FWICS no such
directory ever existed and the bashrc file was always directly inside
the package directory.

Without this change, pexpect's bashrc is not loaded and tests fail
when user's bashrc results in a long prompt.  In my case, they failed
on a system with a 12-character hostname (and passed on a system
with a 6-character hostname).

Prevents usage of stdin by (python) executables that are called during completion generation. This prevents the completion locking up the entire shell when the python script is broken i.e. it enters an interactive mode (REPL) instead of generating the completions, as expected.